SCR Solutions engineered an award-winning AIG retrofit for MID’s Woodland Generation Station in Modesto, CA, earning CCJ’s 2025 “Best of the Best” Award for performance improvements.
Celebrating Award-Winning Innovation
SCR Solutions LLC is proud to announce that its work at the Modesto Irrigation District (MID) Woodland Generation Station Unit 2 in Modesto, CA has been recognized with a 2025 “Best of the Best” Award from Combined Cycle Journal (CCJ). The project earned top honors in the Performance Improvements category for delivering measurable efficiency gains and emissions reductions through a comprehensive retrofit of the plant’s ammonia injection grid (AIG) system.
The Challenge: Tightening NOx and Ammonia Slip Limits
MID’s Woodland Generation Station—a LM6000 combined-cycle gas turbine commissioned in 2003—had long faced challenges maintaining emissions compliance during transitions between fired and unfired operation. Fluctuations in flue-gas flow patterns caused uneven ammonia distribution, resulting in localized high slip, inconsistent NOx control, and ongoing operational adjustments to stay within permit limits.
The Solution: Engineering a Smarter AIG
SCR Solutions was engaged to diagnose and correct the problem. The team began with a comprehensive inspection and advanced computational fluid dynamics (CFD) modeling to visualize how ammonia mixed and flowed through the SCR ductwork. The model revealed significant distribution imbalances and bypass zones caused by the original AIG design.
To address these issues, SCR Solutions engineered a complete AIG retrofit that included:
- Increasing the number of AIG lances from 24 to 50 and doubling injection points.
- Adding top and bottom lances to eliminate dead-flow regions.
- Installing integral mixing plates on each lance for improved uniformity.
- Incorporating side-wall fairings and extended flow baffles to reduce bypass.
- Using laser scanning and 3D modeling to ensure fabrication accuracy despite limited OEM documentation.
All components were fabricated in New Jersey and shipped to California, where the retrofit was completed on an accelerated 12-week schedule—from design through installation.
The Results: Proven Performance Gains
Following installation, MID conducted a detailed stack test comparing pre- and post-retrofit results. The improvements were immediate and significant:
- 83% reduction in ammonia slip (from 3.54 ppmvd → 0.59 ppmvd)
- 16% reduction in ammonia consumption, translating to lower operating costs
- Consistent NOx compliance across all load conditions
- Extended catalyst life through more uniform ammonia distribution
- Enhanced operational flexibility during mode transitions
The retrofit achieved these results without extended downtime, allowing the plant to remain a reliable contributor to California’s clean-energy generation mix.
Collaboration and Recognition
SCR Solutions congratulates the Modesto Irrigation District team, including Paul Mercer (Plant Manager), Richard Behler (Generation Supervisor), and Michael Miller (Environmental Compliance Specialist), for their leadership throughout the project. Their commitment to continuous improvement and environmental performance exemplifies the best practices recognized by CCJ’s annual awards.
About SCR Solutions
Based in Clinton, New Jersey, SCR Solutions provides specialized engineering, CFD analysis, and field implementation for selective catalytic reduction (SCR) systems worldwide. From AIG design to catalyst management and system optimization, SCR Solutions helps utilities and industrial operators achieve cleaner, more efficient, and more reliable emission control performance.
Read the full announcement on Combined Cycle Journal
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